Digital Video Digital Video BroadcastingBroadcasting

Final Custom Implementation DSP Course

Alireza Mazraee FarahaniSpring 2010

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Class presentation for the course: “Custom Implementation of DSP Systems” All the materials are copy rights of their respective authors as listed in references.

DVB Overview DVB Overview DVB Project is an industry-led consortium of over 300

companies The DVB Project was launched on 10th September, 1993 In 1995 it was basically finished and became

operational There are several sub-standards of the DVB standard

DVB-S (Satellite) – using QPSK – 40 Mb/s DVB-T (Terrestrial) – using QAM – 50 Mb/s DVB-C (Cable) – using OFDM – 24 Mb/s

These three sub-standards basically differ only in the specifications to the physical representation, modulation, transmission and reception of the signal

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DVB Overview DVB Overview (Cont.)(Cont.) The DVB stream consists of a series of fixed

length packets which make up a Transport Stream (TS).

The packets support ‘streams’ or ‘data sections’. Streams carry higher layer packets derived from

an MPEG stream. Data sections are blocks of data carrying

signaling and control data. DVB is actually a support mechanism for MPEG. One MPEG stream needing higher instantaneous

data can ‘steal’ capacity from another with spare capacity.

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Digital TV Standards Digital TV Standards Adoption MapAdoption Map

.

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DVB Packets (cont.)DVB Packets (cont.)

MPEG-2 Transport MUX Packet

Randomized transport packet: Sync Bytes and randomized Data byte

Reed-Solomon RS(204,188,8) Error Protected packets.

Data structure after outer interleaving: Interleaving Depth I=12 Bytes

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DVB PacketDVB PacketThe DVB Transport stream consists of a series of

packets204 bytes long, 188 bytes carry information and the

other16 bytes carry an outer Reed-Solomon code. The

packet isshort and can survive a noisy channel subject to

interference.188 Bytes 16 Bytes

Information Reed Solomon Parity block

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Applied Process to Data Applied Process to Data StreamStreamTransport multiplex adaptation and

randomization for energy dispersal;Outer coding (i.e. Reed-solomon code);Outer interleaving (i.e. Convolutional

interleaving);Inner coding (i.e. Punctured convolutional

code);Inner interleaving (bit-wise or symbol

interleaving are block based);Mapping and modulation;Orthogonal frequency division

multiplexing (OFDM) transmission.7

DVB Functional Block DVB Functional Block DiagramDiagram

[7]8

Randomization /De-Randomization /De-Randomization Randomization

In order to ensure adequate binary transitions, the data of the input MPEG-2 multiplex shall be randomized in accordance with the configurations depicted in the following figure[7]:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Initialization: PRBS = 100101010000000

Enable

InputData OutputData

After the 1st byte of each frame : ONFor the 1st byte of each frame :OFF

Note1

Note1:

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Randomization /De-Randomization /De-Randomization (Cont.)Randomization (Cont.)The polynomial for the Pseudo

Random Binary Sequence (PRBS) generator shall be:

1 + X14 + X15

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Reed‐SolomonReed‐SolomonReed-Solomon RS (204,188, t = 8)

shortened code shall be applied to each randomized transport packet (188 byte) to generate an error protected packet.

Reed-Solomon coding shall also be applied to the packet sync byte, either non-inverted (i.e.47HEX) or inverted (i.e. B8HEX).

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Reed‐Solomon (Cont.)Reed‐Solomon (Cont.)All of the following additions and

multiplications are performed in the Galois field.

The Field Generator Polynomial is: p(x) = x8 + x4 + x3 + x2 + 1

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Reed‐Solomon (Cont.)Reed‐Solomon (Cont.)

[7]13

Outer InterleaverOuter Interleaver

M

2*M

3*M

11*M

0

1

2

3

11

1byte per position

1byte per position

[7]

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Outer Outer Interleaver(Cont.)Interleaver(Cont.)Convolutional byte-wise interleaving with depth I = 12 shall be applied to the error protected packets. This results in the interleaved data structure.

The interleaver may be composed of I = 12 branches, cyclically connected to the input byte-stream by the input switch.

Each branch j shall be a First-In, First-Out (FIFO) shift register, with depth j × M cells where M = 17 = N/I, N = 204.

The cells of the FIFO shall contain 1 byte, and the input and output switches shall be synchronized.

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Outer DeinterleaverOuter Deinterleaver

M

2*M

3*M

11*M

9

10

11

8

11byte per position

1byte per position

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Inner CodingInner CodingThe system shall allow for a range of

punctured convolutional codes, based on a mother convolutional code of rate 1/2 with 64 states.

This will allow selection of the most appropriate level of error correction for a given service or The generator polynomials of the mother code are G1 = 171OCT for X output and G2 = 133OCT for Y output.

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Inner Coding(Cont.)Inner Coding(Cont.)

1bit delay

1bit delay

1bit delay

1bit delay

1bit delay

1bit delay

Input Data

X Output (G1=171 octal)

Y Output (G2=133 octal)

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Inner interleavingInner interleavingThe inner interleaving consists of bit-wise

interleaving followed by symbol interleaving. Both the bit-wise interleaving and the symbol interleaving processes are block-based.

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Viterbi DecoderViterbi Decoder

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Viterbi Decoder(Cont.)Viterbi Decoder(Cont.)

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ReferencesReferences[1] U. H. Reimers, "DVB-The Family of International Standards for Digital Video Broadcasting-Invited

Paper," Proceedings of the IEEE, vol. 94, no. 1, pp. 173-182, Jan. 2006.[2] Vangelista, L. ; Benvenuto, N. ; Tomasin, S. ; Nokes, C. ; Stott, J. ; Filippi, A. ; Vlot, M. ; Mignone, V. ;

Morello, A. ; , "Key technologies for next-generation terrestrial digital television standard DVB-T2," Communications Magazine, IEEE , vol. 47, no. 10, pp. 146-153, Oct. 2009.

[3] Reljin, I.S. ; Sugaris, A.N. ;, "DVB Standard Development," in Telecommunication in Modern Satellite, Cable, and Broadcasting Services, 2009. TELSIKS '09. 9th International Conference on, Nis, 2009, pp. 263-272.

[4] W. Fischer, Digital Video and Audio Broadcasting Technology-A Practical Engineering Guide Series: Signals and Communication Technology, 3rd ed.. Springer Heidelberg Dordrecht London New York, 2010.

[5] Jiehan Zhou ; Zhonghong Ou ; Rautiainen, M. ; Koskela, T. ; Ylianttila, M. ;, "Digital Television for Mobile Devices," Multimedia, IEEE , vol. 16, no. 1, pp. 60-71, 2009.

[6] Nilsson, A. ; Tell, E. ; Liu, D. ; , "An 11 mm , 70 mW Fully Programmable Baseband Processor for Mobile WiMAX and DVB-T/H in 0.12 m CMOS," Solid-State Circuits, IEEE Journal of , vol. 44, no. 1, pp. 90-97, Jan. 2009.

[7] Digital Video Broadcasting (DVB);Framing structure, channel coding and modulation for digital terrestrial television, European Broadcasting Union

[8] DVB-T - Wikipedia, the free encyclopedia.[9] Digital Broadcasting: an introduction to ISDB, DVB and ATCS, Presentation slides,

Lieboud Van den Broeck, 2006

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